1. Field of the Invention
The present invention relates generally to hand operated clipping tools and more specifically to a single handed tool for trimming horse hooves.
2. Background Information
In the United States and throughout the world, thousands of people keep horses and use them for a variety of purposes including riding, showing, and as draft animals. Horses, of course, have hooves and the hooves must be maintained to prevent damage such as splitting etc. In most cases horses are shod and the person who cares for the horse""s hooves and applies the horse shoes is most often referred to as a farrier.
Horse hooves grow and probably the most important aspect of hoof maintenance and preparation for shoeing is to keep the hooves trimmed. Trimming a horse hoof can be a difficult task. Horse hooves are very tough and it is physically difficult to cut through the material. In addition, horses are large animals and it is often difficult to control the animal during the trimming process.
A variety of tools have been developed and used by farriers and others to aid the hoof trimming process. The earliest tools were simple knives or saws, but a number of long handled clippers have also been invented. Such clippers ordinarily rely upon the mechanical advantage obtained when relatively long handles are connected to relatively short cutting arms by a hinge. This principal of mechanical advantage is illustrated by a pair of common pliers, for instance. The handles of the pliers move a relatively greater distance than the working arms of the pliers and, the pressure applied by the working arms of the pliers is relatively greater than the pressure applied to the handles. This principle is referred to as mechanical advantage in this application.
Known horse hoof clippers which apply the mechanical advantage described above have an inherent problem: they take two hands to operate because the distance the handles must travel to apply sufficient force to cut a hoof is greater than may be accomplished with one hand. That is, in order to provide sufficient force to trim a horse""s hoof, the handles must start from a position further apart than the five or six inches which can reasonably be controlled by the span of one hand. Therefore, the farrier must use one hand on each of the handles of the tool to apply the force necessary to trim the hoof. Horses are large animals, and a farrier using both hands to operate a trimming tool often has a difficult time controlling the animal and correctly positioning the hoof for trimming. In addition, women farriers often have a difficult time operating a conventional farrier""s tool because they generally have less grip strength than their male counterparts.
The invention presented in the present application is believed to solve, in a simple and effective fashion, problems which have long plagued farriers attempting to trim a horse""s hoof: a farrier""s tool which allows the farrier to apply sufficient force to trim the hoof with a single hand and which leaves one hand free to control the horse and properly position the hoof.
The ideal farrier""s tool should provide a method by which a farrier may trim a horse""s hoof using one hand. The ideal farrier""s tool should also provide sufficient mechanical advantage to trim a hoof without requiring an unreasonable amount of effort. The ideal farrier""s tool should also provide for a straight cut rather than the elliptical cut provided by a conventional farrier""s tool. The ideal farrier""s tool should also be adaptable to other uses which require a similar mechanical advantage and one handed operation. The ideal farrier""s tool should also be simple, rugged, inexpensive, and easy to use.
The farrier""s tool of the instant invention employs the mechanical advantage of having a pair of handles which are hinged such that they are relatively longer than the cutting arms of the tool. In addition, the farrier""s tool incorporates a cam which increases the mechanical advantage so that the tool may apply sufficient pressure to trim a horse""s hoof with the operator using a single hand. That is, even though the handles move only the five or six inches which may be spanned by a single hand, sufficient force is applied to trim the hoof. A conventional farrier""s tool is like a pair of pliers in that it is a machine which uses a single fulcrum or pivot point. The cam of the instant invention is actually a part of a double fulcrum device. By employing a double fulcrum or two pivot point configuration, the farrier""s tool of the instant invention provides approximately twice the mechanical advantage of a single fulcrum machine.
A bottom handle is provided which is bent such that the cutting end of the bottom handle is lower than the handle end of the bottom handle. A straight lever having the same length as the bottom handle is rotatably connected to the handle end of the bottom handle by a hinge pin. A bottom cutting assembly protrudes upward from the cutting end of the bottom handle and a top cutting assembly protrudes downward from the cutting end of the lever such that a bottom cutting blade in the bottom cutting assembly meets a top cutting blade in the top cutting assembly when the farrier""s tool is in a closed position. For purposes of this application, the cutting end of the farrier""s tool is referred to as the forward end and the handle end is referred to as the rearward end.
A cam having a generally triangular shape is also provided. One vertex of the cam is rotatably attached to the lever rearward of the top cutting assembly by means of a lever cam pin through the lever. The forward end of a top handle is rotatably affixed to the top forward vertex of the cam by means of a forward top handle cam pin. Rearward of the forward top handle cam pin, the top handle is also affixed to the top rearward vertex of the cam by a rearward top handle cam pin. The use of the rearward top handle cam pin in the preferred embodiment of the instant invention is to provide stability to the device, but a cam rotatably affixed at just two points, at the lever cam pin and the forward top handle cam pin, would also work.
The lower end of a control arm is rotatably affixed to the bottom handle by a control arm pin just rearward of the bottom cutting assembly. The upper end of the control arm is rotatably affixed to the forward top handle cam pin. A spring is interposed between the bottom handle and the lever just rearward of the cutting assemblies which tends to force the cutting assemblies and the bottom handle and the top handle apart.
In operation, the spring forces the top and bottom handles apart until they reach a maximum separation of the usual span of a single hand. The portion of the hoof to be trimmed is placed between the now separated blades of the cutting assemblies and the tool closed by the operator forcing the top handle toward the bottom handle. Because the mechanical advantage of having longer handles than cutting arms is amplified by the action of the cam, the farrier can apply sufficient force to cut through the hoof material using a single hand.
Although the farrier""s tool of the instant invention is described above as having cutting blades and cutting assemblies, the tool could also be adapted for additional uses. For example, by replacing the cutting assemblies with punch type heads, the device could be used for placing ear tags on cattle.
One of the major objects of the present invention is to provide a farrier""s tool which may be used to trim a horse""s hoof using a single hand.
Another objective of the present invention is to provide a farrier""s tool with which a horse""s hoof may be trimmed using a single hand without requiring the application of an unreasonable amount of force with a single hand.
Another objective of the present invention is to provide a farrier""s tool which provides for a straight cut rather than the elliptical cut provided by a conventional farrier""s tool.
Another objective of the present invention is to provide a farrier""s tool which may be adapted to other uses which require a similar mechanical advantage and one handed operation.
Another objective of the present invention is to provide a farrier""s tool which is simple, rugged, inexpensive, and easy to use.